Despite the Meteorological Agency's alerts for an "extraordinary situation" anticipated from powerful Typhoon Wipha, no evacuation advisory was issued on Izu-Oshima, a small island south of Tokyo in the Pacific, where at least 22 people were killed and dozens remain missing.

The failure to get residents to safety has angered those who lost their homes and has left many questions to address about the steps authorities took to issue warnings.

The Meteorological Agency has established yardsticks for issuing special warnings to municipalities when "once in 50 years" heavy rain is forecast — for periods of three hours and 48 hours.